"The anger, the hatred, the bigotry that goes on in this country is getting to be outrageous…[U]nfortunately, Arizona I think has become sort of the capital. We have become the Mecca for prejudice and bigotry."

As I write, it is far too soon to offer a firm judgment on the part played in causing these crimes by politicians who have glorified the use of weapons and by radio and television demagogues. Let us assume, however, that they did help to create a climate in which Jared Lee Loughner thought he was justified in trying to kill Congresswoman Giffords and those who gathered to meet her. If so, what is to be done?

Unfortunately, there is no easy answer. It seems unlikely that anyone will be able to identify something said by someone, or several things that were said, that directly led to the shooting. If political rhetoric was a factor, it is likely that it was – as Sheriff Dupnik suggested – in creating a climate of anger, hatred and bigotry.

Much attention in the wake of the shooting has focused on Sarah Palin's website. It included a series of maps posted in March 2010 of congressional districts that the Tea Party hoped to capture in November's election. The crosshairs of a rifle sight marked each target district. Congresswoman Giffords had spoken about the use of such imagery, pointing out that it has "consequences". Did it have consequences in the case of Loughner, her would-be assassin? We have no way of knowing, and probably will never know.

Just banning use of the particular images, such as those that appeared on Sarah Palin's website, would probably do little good. One can readily imagine myriad variations that could convey a similar message to an individual like Loughner. If an attempt were made to use the law to prohibit any expression that might have an effect on him, it could only be done through legislation that gives law enforcement authorities broad power. Such legislation would have to authorise them to use criminal sanctions against any expression that might inspire someone, somewhere to commit violence. The authorities would have to have wide discretion.

Of course, American constitutional law allows nothing of the sort. In the unlikely event that Congress were to adopt legislation making it a crime to use words or symbols that look violent or threatening to public officials, as proposed by one member in reaction to the attack on Congresswoman Giffords, it would be struck down by the courts. A specific threat of violence against a specific person can be made a crime. It can also be a crime to incite violence in circumstances when there is an imminent threat that violence will take place. Beyond that, however, American commitment to the freedoms guaranteed by the First Amendment does not permit sanctions.

There are also good reasons in public policy not to permit broader law enforcement powers. Experience elsewhere indicates that such powers are mainly used by officials as a means of punishing political dissenters. Where expression is concerned, it is essential that the state should have as little discretion as possible when to use the power of the law. Because expression can take and does take so many different forms, providing the authorities with broad discretion is particularly subject to abuse.

If criminal sanctions are not the means to control the anger, hatred and bigotry blamed by Sheriff Dupnik for the murders and attempted murders in Arizona, is there an alternative? Probably the only one is the traditional remedy for bad speech: more speech. That is, it is important that those who share the sheriff's views should speak out clearly and forcefully in denouncing the purveyors of anger, hatred and bigotry.

We cannot, and should not, use the law to stop irresponsible politicians like Sarah Palin from expressing their views, even when those views could influence a deranged person who has ready access to dangerous weapons. But we should make clear our contempt for those views.

Hundreds line Tucson's streets to pay respects to Christina Taylor Green, nine, the youngest victim of the gun attack by Jared Lee Loughner that left six dead and congresswoman Gabrielle Giffords fighting for her life